Preparation of 2-chlor-meta-5-xylenol



Patented June 6, 1944 2,350,677 PREPARATION or 2-CHLOR- m gma-s V XYLENOL George William Gladdemoswaldtwistle, England,

assignor to William Wiggins Cooker, Accrington,

England No Drawing. Application May 8, 1940, SerialNo.

334,089. In Great Britain May 20, 1939 2 Claims. (01. 260-4523) This invention relates to improvements in preparation of-2-chlor-meta-5-xylenol, i. e. 1:3-dimethyl-2-chlor 5-hydroxybenzene.

This substance, which is useful as an antiseptic, is usually prepared by the chlorination of met'a-xylenol (1--35), which is obtained by working up'and crystallizing an intermediate obtained since it appears that the crude meta xylenol intermediate usually contains more meta- Xylenol than it is possible to isolate by crystallization, and that the corresponding chlor-body can be isolated from the chlorination product with less loss.

It might have been expected that thi process would increase the difiiculty of purification on account of possible chlorination of impurities, but in practice this apparent difiiculty is notusually observed.

It appears that the success of this method of isolation is dependent on the reactivity of the meta-xylenol, and the relative insolubility of the final product in the reaction mixture.

The intermediate may be any distillation fraction containing substantial quantities of meta- 'xylenol, e. g. say to by weight capable of isolation by crystallization alone, thoughthe actual content of meta-xylenol may be much higher. 7

Intermediate fractions which will give 22 to 25% by weight of technical meta-xylenol m. p. about 60 deg. C. when worked up by crystallizawhich would contain very substantial quantities of meta-xylenol. There is no doubt that with such fractions, and with obvious modifications this method could be applied. The invention-is mainly concerned only with fractions that can be more easily obtained and examples of such fractions and their isolation to the final product will be given later.

Chlorination can be accomplished by the direct action of chlorine on the intermediate fraction, the chlorine being passed into the material from cylinders or produced in situ in any obvious way, but we prefer to use sulphuryl chloride as better yields can be obtained using this material.

The determination of meta-xylenol in tar acid containing that material is not easy, and there does not appear to be any reliable'and convenient method of estimation. It has therefore been necessary to use rather empirical methods for the determination of suitable material, which, while they give us no actual indication of the amount of meta-xylenol present, they do give a measure by which we can assess the raw material. Earlier work on this intermediate was concentrated on fractions that would respond'to a certain method of testing. In further examination of various intermediates it was found that another test can be usefully applied. Suitable materials are defined as follows:

They are essentially intermediates in the manufacture of meta xylenol and have a distillation range between 218 and 222 deg. C. at 760 mins.

' Hg. pressure, and having a-crystallizing point of tion alone can conveniently be used for this process quite conveniently and the limiting higher concentration of meta xylenol that could be used is dependent on the relative ease of isolation of such a fraction. It would be possible by means of extraordinary care, or by adding crystalline meta 20 degrees centigrade or better. The preferred material can be'further defined in one of two methods:

Method 1 g If equal weights of theintermediate andmeta- 5 -xylenol are taken and heated together in a tube until the tube is filled with vapour and. any water expelled and allowed to cool, the freezing point will be about 45 deg. C. or better. In the cooling, precautions must be taken to prevent any water being absorbed, the usual method being to plug the end of the tube with a calcium chloride trap. Furthermore, the meta-5-xyleno1 used in the above test should have a freezing point of at least 64 deg. C.

Method 2 A suitable quantity of the meta-xylenol intermediate is taken and placed in a tube and carefully heated to expel water vapour and cooled,

precautions being taken to avoid any absorption xylenol to the intermediate to make mixtures of Water by means of a suitable trap such as one case anyaddition of pure usually be pointless.

rately as possible by means of a flow-motor.

.rectly, this point is quite sharp and the temperature is noted. Two or three estimations should be done to ensure that the correct point has been obtained. A melting point of 25-3 3;C. is desirable. Broadly speaking the preferred intermediate are those which comply with the above tests. But we may use any intermediate obtained from tar acids by distillation alone, i. e. without fur-- ther or substantial further purification by crystallisation. The intermediate might'be enriched by addition of pure metaxylenol but a. major proportion of distillate would be present and many metaxylenol; would EXAMPLE 1 546 grams of intermediate xylenol fraction (having a crystallising point vof .45 C., when mixed with an equal weight ofmeta-S-xylenolas defined in method (1)) are placed in a suitable vessel, equipped with'stirring gearand 273 grams of sulphuryl chloride are added slowly. The temperature rises in the course of the reaction to about 40 C. When all the sulphuryl chloride is added the reaction mixture is heated to 80 C. and the acid gases removed asfar as possible by air-blowing or any other suitable means; On cooling a quantity of the required chlor xylenol separates out and is removed from the mother liquor. Further quantities of the material required can'be isolated by vacuum distillation of the mother liquors and further crystallisation. In all 200 to 208 grams of material substantially 2-chl0r meta-S-xylenol can 'be obtained having a melting point of 112 to 115 C. The material can be purified if desired by crystallisation from a solvent such as a hydrocarbon. q I

EXAMPLE 2 V 100 grams of a meta-xylenol intermediate (having a crystallising point of 45.75" C. when mixed with an equal weight of meta--xylenolas defined by method (1)), is placed in a suitable vessel and 31.6 grams of chlorine passed in, in

about 30 to 40 minutes, the temperature being kept between 25-30 C. during the course of the reaction. The chlorine is determined as accu- A yield of 25 grams of the desired product is obtained when heated up, acid gases removed and crystallised as in Example (1) When a further 100 grams of the same metaxylenol intermediate is treated with 60 grams of sulphuryl chloride at approximately the same temperature, and using the same method of isola- 5 tion, a yield of 37 to 40 grams of the desired product is obtained. (60 grams of sulphuryl chloride corresponds closely with 31.6 grams of chlorine).

EXAMPLE 3 1165 lbs. of an intermediate meta-xylenol fractionas abovedefined and having a melting point of 31.25 C.'(see method (2)), are placed in a suitable vessel, equipped with means for agitation and with. provision for heating and cooling. -The vessel is also preferably closed and provision made for the escape of acid vapours and for the running in of sulphuryl chloride. Further, it is -very desirable that the vessel and component parts should be fabricated in acid resisting material, or alternatively lined with acid resisting -materia1. 4

. i Thetemperatureofthe charge in the vessel is maintained at a temperature which will just keep the material in solution and 8.33 lbs. of. sulphuryl cl loride; are. added with agitation during the course'of 6 to 7 hours. During the course of the addition the temperature tends to rise and the reaction mass may have to be cooled. It is desirable that the temperature during this partof the process should bev kept between and C. :T-he batch is then heated to 80? C. and the acid gases removed as far as possible by air blowing, or other suitable means. On cooling to 18 C. or lower, the desired chlor-xylenol separates out and can be removed from the mother liquor by the usual means such as filtration or by means of a centrifuge. The crystals arethen washed with 18150 20 gallons of benzene. I The average yield on five batches treated in 40 this manner-was 522 lbs..of mate rial melting at aboutl14" C.. I declare that what I claim is:

- 1; The process of preparing 1 :3-dimethyl-2- chIor-B-hydroxybenzerie which consists intreating a crude metaxylenol tar acid fraction, containing a large proportion of impuritiesand having a distillation range between 218 C. and 222 C. at 760mm. Hglwitha chlorinating agent selected from the group consisting of elementary chlorine and sulphuryl chloride capable of'producing the 2-ch1oro derivative and separating said 2-chloro derivative by crystallisation.

' 2. The process of preparing 1:3. dimethyl-2- chloro-5-hydroxybenzene which consists in reacting a crude metaxylenol tar acid fraction, containing a large "proportion of impurities and having a distillation range between 218 C. and

' 222 C. at 760 mm. Hg. with sulphuryl chloride and separating crystalsof the desired 2-chloro body by cooling the hot reaction-mixture.

I GEORGE WILLIAM GLADDEN. 

